Talk:How to write math on a typewriter

How to write math on a typewriter? I think the greatest problem with this is that most of us do not possess a typewriter. Peter Luschny 21:40, 4 October 2011 (UTC)

Funny. Maybe there is a better title for this.

Seriously, though, the typewriter is a good way to express the concept here (maybe not the best, but good enough, I think). Here on the wiki side we can avail ourselves of fancy things like power towers: $5^{4^{3^{2}}}$. But on the sequences side? Alonso del Arte 05:09, 5 October 2011 (UTC)

Alonso, before the editors decided to give OEIS a lobotomy there were a few happy days where such a thing was indeed possible. Perhaps OEIS should downgrade? By the way: Your considerations overlap in part with the discussion on the talk page of the style sheet. Talk:Style_Sheet#Operations_over_ranges Peter Luschny 19:12, 5 October 2011 (UTC)

That's right. Now that you bring this to my attention, I think this page should be descriptive rather than prescriptive, and leave the prescribing to the Style Sheet. Alonso del Arte 15:33, 6 October 2011 (UTC)

Yes, I agree. And the issue with the typewriter can now also be solved: http://blog.makezine.com/2012/08/30/mechanical-typewriter-keyboard-for-ipad/ Peter Luschny 14:13, 10 December 2012 (UTC)

More seriously...

I think we understood that "typewriter" means "linearized notation using ASCII characters" for math formulae ; actually in some sense typewriters could do more than we can do on OEIS -- they could produce all kind of "composite" characters by using "backspace" (≠ delete...) and also 2-dimensional formulae which are not (yet) allowed on OEIS...

OTOH, I don't fully agree with some statements, like " := comes from programming languages ". I think it is good mathematical practice to use := (or you see "=" with Δ or "def" on top of it, but this does not clarify the concerned side) to distinguish a definition from an equality. — M. F. Hasler 19:17, 20 January 2013 (UTC)

• I like the statement of Niklaus Wirth: "A notorious example for a bad idea was the choice of the equal sign to denote assignment."[Wikipedia] I think that the use of := as the assignment operator does go back to (the programming language) Pascal (Wirth). I haven't seen mathematicians use := for definitions before the arrival of Pascal. But this is then neither a mathematical symbol nor an language operator: it is a meta-symbol, one of the rare cases, where this layer of mathematics shines through and is given an extra symbol by (some) mathematicians. Peter Luschny 20:33, 20 January 2013 (UTC)

I could be wrong about those coming from programming languages, but I'm pretty sure that's where most people know them from. Alonso del Arte 23:53, 20 January 2013 (UTC)

On page 2 of "Elliottt H. Lieb, Michael Loss, Analysis, 2nd edition." the notations $a:=b$ and $b=:a$ both mean $a$ is defined by $b$.

In some scripting languages (e.g. within Macromedia Director, but that's old...), there was set a to b and put b into a (and I think I've even seen somewhere, or maybe it was b -> a instead?) the notation b =: a to mean put b into a). — Daniel Forgues 00:46, 21 January 2013 (UTC)

The notation with arrows goes back to APL. It is the left arrow a ← b. This is to this day the preferred symbol for the assignment operator when writing pseudo-code.

Wikipedia has a nice article about this: "A key development in the ability to use APL effectively, before the widespread use of CRT terminals, was the development of a special IBM Selectric typewriter interchangeable typeball with all the special APL characters on it. This was used on paper printing terminal workstations using the Selectric typewriter and typeball mechanism, such as the IBM 1050 and IBM 2741 terminal. Keycaps could be placed over the normal keys to show which APL characters would be entered and typed when that key was struck." Peter Luschny 07:11, 21 January 2013 (UTC)

Amazing, APL was symbolic in a big way, cool!

"The APL programming language is distinctive in being symbolic rather than lexical: its primitives are denoted by symbols, not words."

See:

APL (programming language)—Wikipedia.org.

APL syntax and symbols—Wikipedia.org.

— Daniel Forgues 03:24, 22 January 2013 (UTC)